Use of foster parents in species conservation may cause conflicting objectives: hybridization between Lesser White-fronted Goose Anser erythropus and Barnacle Goose Branta leucopsis

Following the use of Barnacle Geese Branta leucopsis as foster parents in a conservation program for the endangered Lesser White-fronted Goose Anser erythropus in Sweden 1981–1999, mixed breeding pairs of the two species were established in the wild. We find indications that this was related to shared moulting habits of the two species in the Bothnian Sea during late 1990s. Starting in 2003, five mixed pairs produced at least 49 free-flying hybrid offspring until 2013, when the last breeding was confirmed. Reported numbers of hybrids did not increase in parallel to the production of young hybrids over time. After 2013, the number of hybrids started to decrease in Sweden and the Netherlands. Lower numbers of hybrids than expected can partly be explained by management actions taken, but may also be associated with low survival due to genetic outbreeding. Mixed pairs and their offspring entirely adopted the migratory habits of Barnacle Geese, overlapping very little with sites used by Lesser White-fronted Geese. We find no evidence that the hybrids ever posed a serious threat to Lesser White-fronted Geese breeding in Fennoscandia.

Diet Induces the Difference of Gut Fungal Communities between Anser erythropus Wintering at Shengjin and Caizi Lakes, China

The gut microbiota play major roles in host nutrition and metabolism, and even potential to cause serious disease for animals and human, however, the knowledge of waterbirds’ gut fungal communities are quite limited at present. In this paper, the gut fungal communities and infer the potential pathogens isolated from the feces of Anser erythropus wintering at Shengjin Lake (SJ) and Caizi Lake (CZ) were investigated based on ITS gene region by using high-throughput sequencing. 1,302,562 valid tags corresponding to 2,102 OTUs were retained from 20 fecal samples, including 10 samples per lake. The OTUs from SJ geese represented seven phyla and 27 classes, seven phyla and 28 classes were identified from CZ samples. Ascomycota, Basidiomycota, Zygomycota and Rozellomycota were the dominant gut fungal phyla in this study, accounted for 61.60%, 35.60%, 1.84%, and 0.30% of the OTUs, respectively. The alpha diversity indices showed significantly different between the geese from SJ and CZ. The Anser erythropus mainly ate Poaceae spp. at SJ, while Carex spp. component was identified at CZ, suggesting that the variations in fungal community between the two lake geese might be induced by different diets. We also observed a fungal pattern with a higher number of significant correlations to bacterial genus, and Ceratobasidium, Tomentella, Paurocotylis, Tuber, Podospora and Mortierella were core fungal genus in the two lake geese. Nine potential pathogenic species were identified in the guts across all samples of Anser erythropus at SJ and CZ, it also showed the relative abundance of potential pathogen was significantly higher from SJ samples than that from CZ samples. These findings expanded our knowledge on the gut fungi for waterbirds, indicating the fungi are highly sensitive to diet at two lakes and should pay more attention to the potential pathogenic species of Anser erythropus.